Course Modules
Introduction to JavaScript
Learn the fundamentals of JavaScript programming language
What is JavaScript?
Setting up your development environment
Basic syntax and data types
Variables and constants
Objects and Arrays
Master JavaScript objects and arrays
Working with Arrays
Array Methods
Object Creation
Object Properties
Functions & Scope
Understanding functions and variable scope in JavaScript
Function declarations
Arrow functions
Function parameters
Variable scope and closures
Understanding Functions and Scope
Functions are one of the fundamental building blocks in JavaScript. They allow you to write reusable code and create powerful abstractions. Understanding scope is crucial for managing variable accessibility and creating maintainable code.
Function Types
// Function Declarations
function greet(name) {
return "Hello, " + name + "!";
}
// Function Expression
const add = function(a, b) {
return a + b;
};
// Arrow Function
const multiply = (a, b) => a * b;
// Default Parameters
const greetUser = (name = "Guest") => {
return "Hello, " + name + "!";
};Variable Scope
// Global Scope
let globalVar = "I'm global";
function scopeExample() {
// Function Scope
let functionVar = "I'm function-scoped";
if (true) {
// Block Scope
let blockVar = "I'm block-scoped";
var varVariable = "I'm function-scoped (var)";
console.log(blockVar); // Works
}
console.log(functionVar); // Works
console.log(varVariable); // Works
// console.log(blockVar); // Error!
}
console.log(globalVar); // Works
// console.log(functionVar); // Error!Closures
// Closures Example
function createCounter() {
let count = 0; // Private variable
return {
increment: () => {
count++;
return count;
},
decrement: () => {
count--;
return count;
},
getCount: () => count
};
}
const counter = createCounter();
counter.increment(); // 1
counter.increment(); // 2
counter.decrement(); // 1